1. Field of the Disclosure
Embodiments of the present disclosure generally relates to the assembly of camera devices within electronic devices and more particularly, to preventing misalignment of the camera devices with the electronic devices when performing assembly processes on the camera devices.
2. Description of the Related Art
Portable electronic devices may allow users to enjoy various content while carrying the devices. Examples of such portable electronic devices include portable terminals, MP3 players, or portable media players (PMPs). Such portable electronic devices are increasing the level of functionality while decreasing the dimensions of the device in accordance with customers' demand.
Portable electronic devices tend to have more diversified functions to meet customers' needs due to their portable nature. Advancing technology allows portable electronic devices to be used as a multi-media player that may function not only as a phone but also as a music player, a video player, a TV, or a game player. Camera devices play a major role in increasing the functionality of the portable electronic devices.
Such camera devices are evolving to have more pixels and more functions including autofocus (AF) or optical zoom.
Camera devices such as compact camera module (CCM), which are commonly small and compact, have various applications, such as mobile phones, personal digital assistants (PDAs), smartphones, or other mobile devices or various information technology (IT) devices, such as toy cameras. To meet the increasing needs of customers, more types of devices are available with a small camera device.
A major part of a camera device is a semiconductor chip (also referred to as an image sensor) which may be implemented as a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) image sensor (CIS). An image of an object may be sensed by the image sensor and stored as data in the memory of the device. The stored data may be displayed as an image through a display panel or other display of the device.
The image sensor may be mounted on a board, e.g., a printed circuit board (PCB) or ceramic board (hereinafter, collectively referred to as a “printed circuit board”), and a cylindrical lens body with a lens may be assembled onto the printed circuit board.
A general structure and an assembly process of a camera device is described below.
The camera device includes a lower module of an image sensor module and an upper module of a lens assembly module that are assembled by separate processes and are then assembled together.
First, the process performed on the lower module of the camera device is described. The lower module of the camera device may include an image sensor and a printed circuit board. Assembly of the image sensor module may be performed via wire bonding or flip chip bonding. In the wire bonding method, the image sensor module may be formed by mounting the image sensor on the printed circuit board by way of a coupling method, such as die bonding. The image sensor mounted on the printed circuit board may be bonded to the printed circuit board using electrical signal lines such as wires or bond pads to electrically connect the image sensor with the printed circuit board (hereinafter, referred to as “wire bonding”), thereby forming the lower module of the camera device.
In the flip chip bonding method, the image sensor module may be assembled by electrically connecting the image sensor to the printed circuit board by directly soldering the solder bumps on the image sensor module to the printed circuit board.
Next, the assembly process performed on the upper module of the camera device is described. The upper module of the camera device may include a lens assembly, a cover glass or infrared (IR) filter (hereinafter, collectively referred to as an IR filter), and a side wall having the same. On the side wall may be mounted a lens assembly including at least one or more lens modules and a correction member that drives the lens module and performs image correction using at least one of automatic driving or manual driving of the lens, thereby forming the upper module. The upper module of the camera device may be joined with the lower module via heat-curing bonding.
Further, the IR filter may be mounted on a lower portion of the side wall or an upper portion of the image sensor module through an adhesive such as epoxy resin.
After the assembly of the image sensor module, the process of aligning the image sensor along the optical axis proceeds and after the upper module is assembled onto the lower module, the lens assembly and the image sensor are aligned to the optical axis.
To place the image sensor and the lens in the same optical focus, the image sensor and the lens need to be aligned while the optical axis is adjusted.
The lower image sensor module, however, may be mounted misaligned on the surface of the printed circuit board due to an uneven mounting surface or the printed circuit board may be misaligned upon assembly of the image sensor and the printed circuit board. As a result, the image sensor and the lens may be misaligned resulting in a misaligned optical axis.
When the image sensor is misaligned, the axis of light coming in may be misaligned, causing a deterioration in product quality of the camera device.
Further, such optical axis misalignment may also happen while the upper module is assembled on the lower module. In other words, in case the side wall has the lens assembly, the lens assembly, after completion of alignment, may be joined with the side wall via an adhesive, such as epoxy resin. In this process, the position of the lens assembly mounted inside the side wall is adjusted. A separate member is required to allow such adjustment to be done from outside the side wall. Further, in order to adjust the lens assembly from inside the side wall, a space is required between the lens assembly and the side wall causing the dimensions of the camera device to increase.
During the above-mentioned process of assembling the camera device, specifically, when mounting the image sensor on the printed circuit board, mounting the lens assembly on the side wall, and mounting and fastening the lens assembly-mounted side wall onto the image sensor module, tilts or other failures may occur due to dimensional tolerances or lack of assembly accuracy leading to a deteriorated resolution of the image quality.
Further, high-resolution camera devices require a higher level of alignment in optical axis between the lens and the sensor as compared with low-resolution camera devices and thus a higher resolution requires a higher assembly accuracy that may result in higher costs in development and production.
Thus, there is a need for a tilt correcting method for camera devices, which may reduce defects by minimizing tilts of the image sensor and lens assembly when assembling a high-resolution camera device and thus enables easier assembly development and savings in production costs.